Create api+scenario tests for listeners

This patch implements listener tests for the Octavia
Tempest Plugin.

Co-Authored-By: Adam Harwell <flux.adam@gmail.com>
Change-Id: I5c0d3a737ff4cc929573c6fb7fbb5d46f1159d80
Story: 2001387
Task: 5965
diff --git a/octavia_tempest_plugin/tests/waiters.py b/octavia_tempest_plugin/tests/waiters.py
index 44138a4..6598fcc 100644
--- a/octavia_tempest_plugin/tests/waiters.py
+++ b/octavia_tempest_plugin/tests/waiters.py
@@ -106,7 +106,7 @@
     :returns: None
     """
     try:
-        return delete_func(*args, **kwargs)
+        delete_func(*args, **kwargs)
     except exceptions.NotFound:
         return
     start = int(time.time())